Radio Access Network (RAN) sharing deployment scenarios are known and methods and abilities to facilitate implementations of these scenarios have been introduced into the 3rd Generation Partnership Project (3GPP) standards since Release 5.
RAN sharing provides a way for network operators (service providers) to reduce their capital expenditure requirements and/or widen the area covered by a cellular communication service when setting up a wireless communications network. Rather than each operator having to provide their own base station and associated equipment for each cell of the network, an operator sharing the RAN of another operator is able to provide their service into areas served by the other operator without having to invest in their own base stations in that location.
Furthermore, by reducing the number of base stations that must be provided and operated, the on-going operating costs can be reduced for the sharing operators. Indeed, each base station may draw a large amount of electricity during operation, and therefore reducing the number of operating base stations may significantly reduce electrical power requirements and may therefore also be considered environmentally friendly.
Typically, sharing of RANs by operators has been a symmetric arrangement in which each operator gets some access to the RAN of the other operator. In the extreme, such an arrangement allows two operators to provide service to the same area with half as many base stations (and therefore with significantly reduced cost) as would be required if no sharing was possible.
RAN sharing is particularly advantageous in areas in which an operator has cell capacity that is underused, as this spare capacity can then be shared with no impact on the original operator's on-going service provision. Furthermore, RAN sharing may be useful in order to ensure that a service provided by an operator is able to reach a certain percentage of the population, which may be specified by license conditions in some countries, without requiring each operator to install expensive capacity in remote areas in which it is likely to be underutilized.
Currently, the standards relating to RAN sharing are limited to two scenarios. In a first scenario, only the RAN base stations themselves are shared by the different operators. In a second scenario, parts of the core network, for example the Evolved Packet Core (EPC) in LTE, can be shared as well as the RAN base stations, further decreasing capital expenditure costs in setting up the network. In each case, sharing of the RAN can be arranged to use split frequencies, in which each operator sharing the RAN has allocated (different) frequency ranges, or may use common frequencies in which the full range of frequencies is available for use by either operator.
The mechanisms for sharing of RANs may also be useful in the case of mergers of operator companies, allowing the two operators to merge their network services without any significant interruptions in service provision.
The recent economic situation has provided further impetus for network operators to reduce costs, and therefore increased the trend to share networks with other operators. However, this trend combined with the uptake of mobile data services resulted in a significant increase in the overall system load without a corresponding increase in capacity.
It is therefore an object of the present invention to improve performance of the communication networks that support RAN sharing.